Has low-elevation Cascade snowpack been declining?

Wow. As a snow enthusiast and amateur weather geek, i am thoroughly impressed with all this research. You have saved me time at my boring office job scanning SNOTEL sites just to see who has the deepest snow pack. I love this stuff. Thank you Mr Andalker!

Couple questions about SNOTEL you might be able to help me with. Does Canada have any similar sites set up? I am curious about snow depths in the BC Ranges and always am wondering who is getting the best winter out there! Any European Countries using something similar? Also, do you have any information on SNOTEL sites themselves and how they work? i know they are operated by NRCS, but how exactly is the data collected? I think they use snow pillows for snow water content but how exactly do they measure total depth? In all of your data analysis, is there any one snow event or series of storms that stands out here in the Pacific Northwest? Thanks again!

Thanks everyone for the comments and compliments, it's nice to see that this work and effort is appreciated. The California Cascades data analysis is still in-progress (snowfall sites done, snowpack sites not yet started), as I was out of town for several days on an impromptu road trip to exactly that region, skiing nice smooth Juneuary corn in the sunshine on Lassen Peak (my first winter summit and ski descent there), Mount Shasta (first winter summit denied at 12000 ft by unexpected extreme gusty winds and dangerous falling ice missiles), and Crater Lake (easy ski tour to The Watchman).

But I'll try to address a few more of the comments now:

Really fine work Amar.  Thanks for so clearly showing these historical trends, particularly of the PDO. Looking at the maximums back in the 50's surely seems to support the Moffet's at Snoqualmie building those dangerously high top off-loading stations on those 1st generation chairlifts.  It put real fear in your gut as a beginner,  as your chair approached the top lift station, which itself was adorned with the broken ski tips of the unwary or distracted who innocently let their skis dangle   

So now for another question: Can you analyze the data to show when enough skiable snow has accumulated, for however many stations you can find.  How much variability is there in the onset of skiing?  Or, is our 'typical' season still averaging  the same mean start, center or overall period?  Should we shift our expectations, or just cool it and be patient, knowing that  the skiing will always return to the mean - which seems to fly in the face of global warming, which I too fear is well on its way.

It would be possible to go through all the data and check when some critical threshold of snowdepth (say 24" or 36") is first reached in each season, for sites which have hourly or daily data. But I have not yet done so for any site, and it would take a large amount of work to do it, either doing it completely manually or by writing a reliable script to extract it (and then manually double-checking). Maybe at some point I may do so for some sites, time and other priorities permitting, but it is not a high-priority yet, and it's hard.

However, unlike most such snowfall-related questions, I really don't have a good idea beforehand what that data might show, whether the date of reaching a skiable depth has been shifting later over the decades or not. So it is an interesting and open question which deserves investigation.

great info.

As a question that is not scientific...but maybe somewhat in the same direction....

Does anybody have the historic opening and closing dates of skiing at Snoqualmie Pass?

As far as I know, that information is not readily available for almost any ski area, and almost all ski areas are very reluctant to release that info publicly. It's simply not anything they want the public to know, for obvious marketing/business reasons! The one exception I've ever seen (there may be others) is Mammoth Mountain Ski Area in California, which publicly posted all of its historic opening and closing dates back to 1968 on its website, along with complete monthly snowfall data too. But Mammoth did so for marketing reasons too: to promote its very long ski season, as it often has the 2nd longest ski season in North America, trailing only Mount Hood Timberline Lodge, and often extending from late October to early July (and even into mid-August in 1995). However, it has fallen far short of that range in the past 3 seasons during the unprecedented California drought, and perhaps not coincidentally, the historic opening/closing data appears to have now vanished from its website.

Although I haven't tried to ask the Summit at Snoqualmie for that data, the likelihood that they would provide it along with permission to post it online seems near-zero, and not worth the effort. But maybe someone should try. Or perhaps try to get it from the US Forest Service for those ski areas which operate under a USFS special use permit (like Snoqualmie, and most other Northwest ski areas). Otherwise, this type of historical data would have had to have been collected by someone in the general public each year for many decades, but I know of no one who has done so. I have it for the last several years for most Northwest ski areas, but that is not nearly long enough to be useful yet.

I'd love to see the same analysis of the interior ranges.  Selkirks, Bitterroots, West Central Idaho, Sawtooths.  I'm seeing big changes (warmer) at the middle elevations there.  So does the U of I.

But does warmer mean less snow?

Unfortunately, I'm not the right person to do that analysis. Without an in-depth familiarity with the snow climatology of a given range or region (i.e. knowing spatial variations such as rain-shadowing, or temporal cycles such as the PDO correlation), it would be easy to make foolish mistakes and egregious errors in the data analysis, and I simply don't have that knowledge for any interior range. I do have the necessary degree of knowledge and familiarity for the entire Cascade Range, plus adjacent portions of the southwestern BC Coast Mountains, the Olympics, Klamath Mountains, and Sierra Nevada in California, so I'm comfortable analyzing data and drawing conclusions for those areas, but not really for any other areas as of yet.

Wow. As a snow enthusiast and amateur weather geek, i am thoroughly impressed with all this research. You have saved me time at my boring office job scanning SNOTEL sites just to see who has the deepest snow pack. I love this stuff. Thank you Mr Andalkar!

Couple questions about SNOTEL you might be able to help me with. Does Canada have any similar sites set up? I am curious about snow depths in the BC Ranges and always am wondering who is getting the best winter out there! Any European Countries using something similar? Also, do you have any information on SNOTEL sites themselves and how they work? i know they are operated by NRCS, but how exactly is the data collected? I think they use snow pillows for snow water content but how exactly do they measure total depth? In all of your data analysis,  is there any one snow event or series of storms that stands out here in the Pacific Northwest? Thanks again!

For British Columbia, the BC River Forecast Centre has a very modest network of hourly snow telemetry sites: only 51 last year, now 50, not all of which have snowdepth sensors, in the entire vast mostly-mountainous province with an area greater than Washington, Oregon, and California combined. There's also a larger network of monthly snow course sites (about 165 active). Luckily the monthly manual snow course data for the current season is readily viewable online.

Viewing data from their telemetry sites is not easy though, as only 7 days of data are readily available for each site as an unformatted CSV file, with telemetry data for the rest of the current season and all the years since 2011 only available on this page as a set of 4 separate files (SWE, snow depth, precip, temperature), each of which includes all telemetry sites ( archived data from the start date through 2011 is available for each site separately, but not for more recent years). Very inconvenient and hard to use, really a maddening and unacceptable situation, but that's how it is. In order to actually view the unformatted CSV data for the last 7 days, I wrote my own viewer script a few years ago, which also converts from metric units: British Columbia Snow Telemetry . I recently got an email from someone who works at BCRFC who says they use my viewer script to easily and quickly view their own telemetry data! Excellent!

For Alberta, snow telemetry and monthly snow course data can be found here, but I haven't really used it much: environment.alberta.ca/forecasting/reports/

Don't know about European snow telemetry.

SNOTEL sites transmit data via the super-cool and ultra-reliable meteor burst communications technology. The snowdepth is measured using an ultrasonic distance sensor looking downward at the snowpack from an arm mounted high on a tower, the same as at NWAC telemetry sites.
Some info about SNOTEL sites can be found here: www.wcc.nrcs.usda.gov/snow/about.html and www.wcc.nrcs.usda.gov/factpub/sect_4b.html
Much more detailed info about and pictures of SNOTEL sites: Idaho Snow Survey Frequently Asked Questions

There have been a number of huge storm cycles (generally those dumping 10 ft or more of snow at many sites) in the Cascades over the 21 seasons since I moved to Seattle from the East Coast. Among the most notable was one in February 1999 which buried chairlifts at Mount Baker Ski Area in the middle of that record-setting 1140" snowfall season, but it's hard to remember details for most of them though without having written something down. The most recent such storm cycle happened last February, and was documented in detail here on TAY: HUGE storm cycle brings 4-14 ft snow Feb6-25,2014!

Very interesting analysis!

I ran across Pederson's "The unusual nature of recent snowpack declines in the North American Cordillera" while looking for information on regional snow pack variability and it seems worth reviewing in this thread:

scholar.google.com/scholar?hl=en&q=The+U...+American+Cordillera

They use tree ring records to establish a snow pack record back to the year 1200. They focus on the rockies instead of the coast ranges but have a bunch of findings that seem relevant to this discussion.

In particular they show that a major driving factor in snow pack is a decade scale phasing in where the major storm tracks go...ie colorado has a good decade when the northern rockies have a bad one and visa versa.

Looking at their graphs the decline since the 50's in the northern rockies and columbia basin could be largely driven by this. However the 50's are actually somewhat average years and the recent years and ~20's era are bellow average when compared to the 1800's and before.

Ie they find a distinct decline in snow pack in the 20'th century which took effect in about ~1900.

I think that the decade scale phasing in storm tracks will confound any analysis of the much shorter record of snowtel data. It might be possible to control for this by looking at retained precipitation or snow versus rain for each individual site?

Amar, I'm no meteorologist and may have missed something so i'm curious to know what your thoughts are.